Oxidation of hydrocarbons



w. H. KING ET A1. 292159472 OXIDATION 0F HYDROCARBONS Y Filed April 2, 1938 639.5* Cown/NW6 FEEE OKI/65N JEM/@H7012 Fa Tae f/wowu HND .Hc/06 ZemQg/gg@ A INVEN'TORS BY m A TTORNEY Patented Sept. 24, 1940 PATENT OFFICE.

OXIDATION' oF mmaooalmorisy William IL King, New Orleans, La., and Clydev Quitman Sheely, State College, Miss.

` Application April 2, 1938, Serial No. 199,636

lclaim.

This invention relates to a newand improved process for the preparation of lchemicalv compounds by the oxidation of aliphatic hydrocarbons in the presence of a catalyst, and more particularly to such 'a process wherein the reaction products comprise aliphatic alcohols, aldehydes and acids.

This application contains matter which has been derived from application Serial No. 108,478, led October 30, 1936 now Patent #2,190,453 and is a continuation-in-part thereof.

The higher aldehydes of the aliphatic series have considerable value as chemical compounds and a number of them have found use in industry as perfumes. The diculties in the way of preparing such compounds, however, have kept their costs so high as to limit their field of usefulness. An improved and simpler method of obtaining such aldehydes would make more accessible a Very desirable class of products. The sameI condition holds in the case of a number of the -higher aliphatic alcohols and acids also, for example those containing in the neighborhood of 8 to 12 carbon atoms. f

An object of our invention is an improved method for the production of alcohols, aldehydes, and acids by the incomplete oxidation of aliphatic hydrocarbons. A further object is such a process in which carefully controlled conditions allow a high degree of efliciency in the preparation of the desired products. A still further object is a process in which the several products obtained may be separated in relatively pure form. Additional objects will be disclosed as the process is further described hereinafter.

We have found that the foregoing objects may be accomplished by the process of our invention which comprises introducing a normally liquid hydrocarbon in the vapor phase into a heated chamber, together with an oxidizing agent comprising a gas containing free oxygen. The oxidation step is carried out in the presence of a catalyst promoting partial oxidation, said catalyst being selected from the group consisting of tetraethyl lead, copper oleate, benzoyl peroxide, nitrobenzene, and other anti-knocking catalysts. Within the reaction chamber the mixed gases and vapors are subjected to a temperature between 250 and 500 C. While the oxidation of the hydrocarbons constitutes an exothermic reac tion, the heat evolved will not be suicient to maintain the desired temperature and external heating will be necessary. It is essential that the reaction period be kept at a relatively short time interval, and we have found 15 seconds to be the maximum allowable time. Preferably we employ a reaction period not greater than 12 seconds, in order that the oxidation may not proceed too far. The reacting materials and reaction products are removed from the heated chamber while still in the vapor p hase and are condensed by any desired method and apparatus under such conditions and in such an atmosphere that further reaction cannot take place. The amount of hydrocarbon will be above the explosive limit in all cases. We have found it desirable to use an amount of hydrocarbon of at least 10% by volume of the gaseous reaction mixture, and preferably between 20 and 40%.

It will be a desirable step in our process also to utilize the unreacted hydrocarbon resulting from the process and to recycle it to an additional similar oxidation step, whereby the advantages of the presence of an excess of hydrocarbon are obtained with no loss in non-reacting material.

The |accompanying drawing shows diagrammatically a ow sheet of one method of carrying out our process. From a reservoir l, the normally liquid hydrocarbon is 4forced through conduit 2 into the preheater 3. The gas containing free oxygen is passed through conduit 4 through the preheater 3, en route to the reaction chamber 5.

Both the vaporized hydrocarbon and the oxygen containing gas pass into the reaction chamber 5 where they become intimately mixed and where a temperature of 250 to 500 C.,is'maintained, said catalyst, promoting partial oxidation, being present, whereby partial oxidation of the hydrocarbons is brought about. The vapors pass out the conduit 6 into separator 1, where any tar formed in the process is separated out. The mixed vapors and gases then pass through condenser 8, where the products capable of condensation become liqueed. The liquid condensate flows into reservoir 9, while a second vessel I0 receives any further condensed product not caught in chamber 9, but condensed in il. The reservoirs 9 and l0 contain the liquefied unreacted hydrocarbon that has passed through the process, and also condensed water and the alcohols, aldehydes and acids resulting from the oxidation process. Such alcohols, aldehydes and acids will commonly be found in the water-insoluble layer. 4

Specic operating conditionssuitable for our process for the production of alcohols, aldehydes, and acids are shown in the following examples. These are to be considered as merely illustrative, however, and not limiting in their application.

Example 1 0.60 cc. of tetraethyl lead was dissolved in 200 cc. of naphtha. This mixture was Vaporized in the usual manner and mixed with air at a temperature of 387 C. The time of reaction was 5.2 seconds and the percentage of hydrocarbon in the reaction mixture was 18.7. There was 20 cc. burned up and the yield obtained was calculated to be 16.17% aldehydes and 13.64% acids.

Example 2 Example 3 One gram of benzoyl peroxide was dissolved in 200 cc. of naphtha and subjected to the oxidation treatment under the same conditions as those of the foregoing examples. The yield was approximately the same as those obtained in the previous examples.

Example 4 One gram of copper oleate was dissolved in 200 cc. of naphtha and subjected to the oxidation treatment set forth in the foregoing examples.

Similar yields were obtained.

The following runs were made in addition to those set forth in the foregoingexamples:

Run

Reaction Reaction time in` temperaseconds ture nc layer Percent Ccs.

HC yield 45 Runs from l5 through 22 used 2 cc. laad toh'aethyl per 1,000 cc.

hydrocarbon.

Runs from 23 through 26 used varying amounts as indicated.

,The method of operation according to the present invention produces alcohols, aldehydes 5o and acids. However, it is especially favorable to the production of alcohols.

'I'he alcohols, aldehydes and acids resulting from the oxidation of hydrocarbons according to to the process of our invention, are products of considerable economic value and of desirable properties, and the process described offers a 5 novel and advantageous method of obtaining such products. Our process is characterized by higher yields and greater efllciency than` any process in the art.

The alcohols, aldehydes and acids may be sepl0 arated from the hydrocarbon condensate and from one another by the use of suitable solvents. In the case of aldehydes, for example, a saturated solution of sodium bisulflte was found desirable for extraction, the bisulilte subsequently 15 being made alkaline and being subjected to steam distillation. The acids were desirably extracted by means of sodium hydroxide solution. The alcohols are preferably extracted by means of phosphoric acid. 20

While our process has been described in detail in theforegoing, it will be understood Athat many variations in procedure may be employed without departing-from the scope of our invention. In the examples cited, a hydrocarbon fraction of a 25 specific distillation range was used, but it would be a highly desirable procedure also to start with a single aliphatic hydrocarbon, for example octane, or a' mixture of octanes.

We wish to'be limited, therefore, only by the 30 following patent claim.y

We claim: A

The process for producing partially oxidized products of normally liquid aliphatic hydrocarbons which comprises'introducing said hydrocar- 35 bons in vapor phase, together with an oxidizing agent comprising a gas containing free oxygen, into a reaction chamber at a temperature between 250 C. and 500 C., maintaining the Y amount of hydrocarbon in the hydrocarbon--oxy-v 40 gen ratio above the explosive limit, reacting said materials for a period not exceeding 15 seconds in the presence of tetraethyl lead, removing the reacting materials and th reaction products from the chamber while still in the vapor phase and condensing the unreacted hydrocarbon and the oxidation products under non-reacting conditions. l

WILLIAM H. KING. f

CLYDE QUITMAN SI-IElEiLY. 

